// @flow

import { cloneLayout, compact, correctBounds } from './utils'

import type { Layout } from './utils'

export type ResponsiveLayout = { lg?: Layout, md?: Layout, sm?: Layout, xs?: Layout, xxs?: Layout };
type Breakpoints = { lg?: number, md?: number, sm?: number, xs?: number, xxs?: number };
type ResponsiveLayoutKey = keyof ResponsiveLayout;
type Breakpoint = keyof Breakpoints;

/**
 * Given a width, find the highest breakpoint that matches is valid for it (width > breakpoint).
 *
 * @param  {Object} breakpoints Breakpoints object (e.g. {lg: 1200, md: 960, ...})
 * @param  {Number} width Screen width.
 * @return {String}       Highest breakpoint that is less than width.
 */
export function getBreakpointFromWidth (breakpoints: Breakpoints, width: number): Breakpoint {
  const sorted = sortBreakpoints(breakpoints)
  let matching = sorted[0]
  for (let index = 1, len = sorted.length; index < len; index++) {
    const breakpointName = sorted[index] as ResponsiveLayoutKey
    let breakpointValue = breakpoints[breakpointName]
    breakpointValue = breakpointValue || 0
    if (width > breakpointValue) matching = breakpointName
  }
  return matching
}

/**
 * Given a breakpoint, get the # of cols set for it.
 * @param  {String} breakpoint Breakpoint name.
 * @param  {Object} cols       Map of breakpoints to cols.
 * @return {Number}            Number of cols.
 */
export function getColsFromBreakpoint (breakpoint: Breakpoint, cols: Breakpoints): number {
  if (!cols[breakpoint]) {
    throw new Error('ResponsiveGridLayout: `cols` entry for breakpoint ' + breakpoint + ' is missing!')
  }
  return cols[breakpoint] as number
}

/**
 * Given existing layouts and a new breakpoint, find or generate a new layout.
 *
 * This finds the layout above the new one and generates from it, if it exists.
 *
 * @param  {Array} orgLayout     Original layout.
 * @param  {Object} layouts     Existing layouts.
 * @param  {Array} breakpoints All breakpoints.
 * @param  {String} breakpoint New breakpoint.
 * @param  {String} lastBreakpoint Last breakpoint (for fallback).
 * @param  {Number} cols       Column count at new breakpoint.
 * @param  {Boolean} verticalCompact Whether or not to compact the layout
 *   vertically.
 * @return {Array}             New layout.
 */
export function findOrGenerateResponsiveLayout (orgLayout: Layout,
  layouts: ResponsiveLayout,
  breakpoints: Breakpoints,
  breakpoint: Breakpoint,
  lastBreakpoint: Breakpoint,
  cols: number,
  verticalCompact: boolean): Layout {
  // If it already exists, just return it.
  if (layouts[breakpoint]) return cloneLayout(layouts[breakpoint] as Layout)
  // Find or generate the next layout
  let layout = orgLayout

  const breakpointsSorted = sortBreakpoints(breakpoints)
  const breakpointsAbove = breakpointsSorted.slice(breakpointsSorted.indexOf(breakpoint))
  for (let i = 0, len = breakpointsAbove.length; i < len; i++) {
    const b = breakpointsAbove[i]
    if (layouts[b]) {
      layout = layouts[b] as Layout
      break
    }
  }
  layout = cloneLayout(layout || []) // clone layout so we don't modify existing items
  return compact(correctBounds(layout, { cols: cols }), verticalCompact)
}

/**
 * Given breakpoints, return an array of breakpoints sorted by width. This is usually
 * e.g. ['xxs', 'xs', 'sm', ...]
 *
 * @param  {Object} breakpoints Key/value pair of breakpoint names to widths.
 * @return {Array}              Sorted breakpoints.
 */
export function sortBreakpoints (breakpoints: Breakpoints): Array<Breakpoint> {
  const keys = Object.keys(breakpoints) as Breakpoint[]
  return keys.sort((a: Breakpoint, b: Breakpoint) => {
    return (breakpoints[a] as number) - (breakpoints[b] as number)
  })
}
